SNHU DAD 220 ACTUAL EXAM SCRIPT 2025/2026
QUESTIONS WITH ANSWERS GRADED A+
✔✔Third normal form - ✔✔All non-key columns depend on the key, the whole key, and
nothing but the key.
✔✔In what situations is redundancy more acceptable? - ✔✔In a database used
primarily for reporting, changes are infrequent and redundancy is acceptable. In fact,
redundancy can be desirable in reporting databases, as processing is faster and
queries are simpler. For this reason, reporting databases may contain tables that, by
design, are not in third normal form.
✔✔Denormalization - ✔✔intentionally introducing redundancy by merging tables.
Denormalization eliminates join queries and therefore improves query performance.
✔✔Aggregate Functions in SQL - ✔✔Used to summarize information from multiple
tuples into a single-tuple summary
✔✔Some common aggregat functions - ✔✔COUNT() - Counts the number of rows
retrieved by a SELECT statement.
MIN() - Finds the minimum value in a group.
MAX() - Finds the maximum value in a group.
SUM() - Sums all the values in a group.
AVG() - Finds the arithmetic mean (average) of all the values in a group.
✔✔GROUP BY clause does what? - ✔✔groups rows with identical values into a set of
summary rows
One or more columns are listed after GROUP BY, separated by commas.
GROUP BY clause returns one row for each group.
Each group may be ordered with the ORDER BY clause.
GROUP BY clause must appear before the ORDER BY clause and after the WHERE
clause (if present).
✔✔What does the numeric function ABS(n) do? - ✔✔Returns the absolute value of n
✔✔What does the numeric function LOG(n) do? - ✔✔REturns the natural logarithm of n
✔✔What does the numeric function POW(x,y) do? - ✔✔Returns x to the power of y
✔✔What does the numeric function RAND() do? - ✔✔Returns a random number
between 0 (inclusive) and 1 (exclusive)
, ✔✔What does the numeric function ROUND(n, d) do? - ✔✔Returns n rounded to d
decimal places
✔✔What does the numeric function SQRT(n) do? - ✔✔returns the square root of n
✔✔What does the string function CONCAT(s1, s2, ...) do? - ✔✔Returns the string that
results from concatenating the string arguments
ex. SELECT CONCAT('Dis','en','gage');
Returns 'Disengage'
✔✔What does the string function LOWER(s) do? - ✔✔Returns the lowercase s
✔✔What does the string function REPLACE(s, from, to) do? - ✔✔Returns the string s
with all occurtences of from replaced with to
ex. SELECT REPLACE("This and that", "and", "or");
returns 'This or that'
✔✔what does the string function SUBSTRING(s, pos, len) do? - ✔✔Returns the
substring from s that starts at position pos and has length len
ex. SELECT SUBSTRING("Boomerang", 1, 4);
returns 'Boom'
✔✔What does the string function TRIM(s) do? - ✔✔returns the string s without leading
and trailing spaces
ex. SELECT TRIM(" test ");
returns 'test'
✔✔What does the string function UPPER(s) do? - ✔✔Returns the uppercase s
✔✔What does the date and time function CURDATE() CURTIME() NOW() do? -
✔✔Returns the current date, time, or date and time in 'YYYY-MM-DD', 'HH:MM:SS',
or'YYYY-MM-DD HH:MM:SS' format
✔✔What does the date and time function DATE(expr) TIME(expr) do? - ✔✔Extracts the
date or time from a date or datetimeexpression expr
ex. SELECT DATE('2013-03-25 22:11:45');
returns '2013-03-25'
SELECT TIME('2013-03-25 22:11:45');
returns '22:11:45'
QUESTIONS WITH ANSWERS GRADED A+
✔✔Third normal form - ✔✔All non-key columns depend on the key, the whole key, and
nothing but the key.
✔✔In what situations is redundancy more acceptable? - ✔✔In a database used
primarily for reporting, changes are infrequent and redundancy is acceptable. In fact,
redundancy can be desirable in reporting databases, as processing is faster and
queries are simpler. For this reason, reporting databases may contain tables that, by
design, are not in third normal form.
✔✔Denormalization - ✔✔intentionally introducing redundancy by merging tables.
Denormalization eliminates join queries and therefore improves query performance.
✔✔Aggregate Functions in SQL - ✔✔Used to summarize information from multiple
tuples into a single-tuple summary
✔✔Some common aggregat functions - ✔✔COUNT() - Counts the number of rows
retrieved by a SELECT statement.
MIN() - Finds the minimum value in a group.
MAX() - Finds the maximum value in a group.
SUM() - Sums all the values in a group.
AVG() - Finds the arithmetic mean (average) of all the values in a group.
✔✔GROUP BY clause does what? - ✔✔groups rows with identical values into a set of
summary rows
One or more columns are listed after GROUP BY, separated by commas.
GROUP BY clause returns one row for each group.
Each group may be ordered with the ORDER BY clause.
GROUP BY clause must appear before the ORDER BY clause and after the WHERE
clause (if present).
✔✔What does the numeric function ABS(n) do? - ✔✔Returns the absolute value of n
✔✔What does the numeric function LOG(n) do? - ✔✔REturns the natural logarithm of n
✔✔What does the numeric function POW(x,y) do? - ✔✔Returns x to the power of y
✔✔What does the numeric function RAND() do? - ✔✔Returns a random number
between 0 (inclusive) and 1 (exclusive)
, ✔✔What does the numeric function ROUND(n, d) do? - ✔✔Returns n rounded to d
decimal places
✔✔What does the numeric function SQRT(n) do? - ✔✔returns the square root of n
✔✔What does the string function CONCAT(s1, s2, ...) do? - ✔✔Returns the string that
results from concatenating the string arguments
ex. SELECT CONCAT('Dis','en','gage');
Returns 'Disengage'
✔✔What does the string function LOWER(s) do? - ✔✔Returns the lowercase s
✔✔What does the string function REPLACE(s, from, to) do? - ✔✔Returns the string s
with all occurtences of from replaced with to
ex. SELECT REPLACE("This and that", "and", "or");
returns 'This or that'
✔✔what does the string function SUBSTRING(s, pos, len) do? - ✔✔Returns the
substring from s that starts at position pos and has length len
ex. SELECT SUBSTRING("Boomerang", 1, 4);
returns 'Boom'
✔✔What does the string function TRIM(s) do? - ✔✔returns the string s without leading
and trailing spaces
ex. SELECT TRIM(" test ");
returns 'test'
✔✔What does the string function UPPER(s) do? - ✔✔Returns the uppercase s
✔✔What does the date and time function CURDATE() CURTIME() NOW() do? -
✔✔Returns the current date, time, or date and time in 'YYYY-MM-DD', 'HH:MM:SS',
or'YYYY-MM-DD HH:MM:SS' format
✔✔What does the date and time function DATE(expr) TIME(expr) do? - ✔✔Extracts the
date or time from a date or datetimeexpression expr
ex. SELECT DATE('2013-03-25 22:11:45');
returns '2013-03-25'
SELECT TIME('2013-03-25 22:11:45');
returns '22:11:45'
